Brian Roth said:LOL...a contributor on this forum...John Roberts....makes comments from time to time..."I need to soak this in beer". <g>
My main effort was to work out the levels through the input module before following that signal through the rest of the desk...ie multitrack program outs/2 mix/aux buses/monitor outs/etc. I've spent 45+ years dealing with analog desks. Never worked with a SW series 40, but the signal flow looked VERY familiar compared to others from that time frame.
Also glad to know you have some very decent test gear instead of a Rat Shack $5.00 meter and "whistling into a mic" for a signal source <g>.
I now need to study the SW docs for the rest of the desk to see how they dealt with internal levels and adjustments.
I consider myself semi-retired but still take on a few projects. Happy to be of assistance!
Yeah at first I was using my Tek analog scope to monitor the generator as well as output from the console, but the waveform on the screen just wasn't clear enough to get a super accurate reading. Hooked up the Agilent instead and it's readout is matching the HP down to several decimal places! Awesome! Gotta love good tools.....and beer! Great combo!
This SW is a bit of a time vampire when it comes to maintenance (at least upfront), but a cool sleeper console. It was designed by the same folks who came up with many of the classic API circuits in the 70's before leaving API to start SW. Although the overall quality is nowhere near that of API (closer to MCI) I've been told directly by a former SW employee who shall remain nameless that the circuitry itself is about as close as they could get to some of the classic API stuff (512c preamp, 550 EQ) without getting sued. But from the research I did it seemed like a great board for the price ($free.99!!!) with the main downsides being crappy, low-value caps and a cheapo patchbay.
I had a buncha Switchcraft patchbays with Mogami tails laying around, so that was the first upgrade, then did double-capacitance and double-voltage Nichi UKZ, UPR, MUSE or Panasonic FM caps in the power supply and throughout the console where appropriate for their application + 5x value Nichicon MUSE main caps in the mic pres.....probably overkill, but hey, why not?
With extreme deference to taking up any more of your time, if you're going to check out the schems anyway, I can't help but ask your thoughts on how it compares to some of the classic API or other 1970's circuits from a design standpoint. I checked out your website and it's clear you have a lot of experience with a lot of different consoles, especially from that era! Your late 70's custom console looks awesome! I especially love the idea of the "D" switch to bypass unecessary circuitry on the busses!
I've tried looking for the 512c schems to compare with my pres (minus the xformer of course)....can't find them anywhere. According to my source this is due to an NDA which is still in effect. But xformer's not withstanding, my pres look nothing like the 312, for which schems are available. On the 550 I really have no clue....too much stuff going on. I know it definitely didn't use TL074's though lol
Anyway, thanks again for everything! I really can't express how much I appreciate the help!